Abstract Background Therapeutic drug monitoring (TDM) of infliximab (IFX) improves efficacy and treatment persistence in inflammatory bowel disease (IBD), yet strategies differ across centers. Population pharmacokinetic (PK) modeling may enable more personalized and dynamic dose adjustment. Although the optimal monitoring approach remains controversial, several studies support proactive TDM of anti-TNF agents to optimize exposure, reduce immunogenicity, and improve long-term outcomes. Aims compare the efficacy, persistence, and safety of a proactive TDM strategy versus a PK model–based approach in IBD patients receiving IFX in real-world practice. Methods Retrospective cohort study including IBD patients treated with IFX in a tertiary center. • Proactive TDM cohort: 2020–2022. • PK-model cohort: 2023–2025 with individualized dose predictions. Clinical, biochemical, and pharmacokinetic data were collected up to 12 months. Main endpoints: clinical and biochemical remission (PCR 5 mg/L, FC 150 µg/g), persistence, intensification, and adverse events. Results A total of 159 patients were included (TDM = 114; PK = 45). Mean age was 46.3 ±16 (TDM) and 43.3 ±16 years (PK); 56.1% and 51.1% were female. Crohn’s disease: 47.7% (TDM) vs 24.5% (PK); ulcerative colitis: 46.0% vs 69.0%. Baseline inflammation differed: PCR 5 mg/L was more frequent in PK (57% vs 28%), whereas FC 150 µg/g and global severity scores were higher in TDM (82.6% vs 72%). During follow-up, a higher proportion of PK-model patients achieved FC 150 µg/g at week 6 (65% vs 45%, p = 0.026) and week 14 (70% vs 51%, p = 0.045). IFX 7 µg/mL at week 14 was more common in PK (70% vs 42%, p 0.001). Intensification was required more often in PK (57.5% vs 25%, p 0.001), while concomitant immunomodulators were more frequent in TDM (45% vs 5.6%, p 0.001). No significant differences were observed in clinical or biochemical remission, persistence, adverse events, or HLA-DQA1*05 distribution at 12 months. Conclusion Both proactive and PK-based monitoring strategies showed comparable long-term efficacy and safety. The PK-model–guided approach was associated with an earlier biochemical response and a trend toward more individualized optimization. These findings support the role of PK modeling as a complementary tool for personalized IBD management, although longer follow-up is needed to confirm whether these early advantages translate into sustained clinical benefit. References: 1. Hanauer SD; Feagan BG, Lichtensten GR et al. Maintenance infliximab for Crohńs disease: The ACCENT I randomised trial. Lancet 2002; 359:1541-15492. 2. Sand BE, Anderson FH, Berntein CN et al. Infliximab maintenance therapy for fistulizing Crohńs disease. N Engl J Med 2004; 350:876-8853. 3. Ben Horin S, Chowers Y. 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Clin Exp Immunol. 2018;192(3):348-365. doi:10.1111/cei.13112 Conflict of interest: Carrillo Palau, Marta: No conflict of interest Morant Domínguez, Andrea María: No conflict of interest Ashok Bhagchandani, Rashika: No conflict of interest Vera Santana, Belén del Carmen: No conflict of interest Medina Chico, Sergio: No conflict of interest Del Rosario García, Betel: No conflict of interest Ramos Lopez, Laura: No conflict of interest Reygosa, María Cristina: No conflict of interest Gutierrez Nicolás, Fernando: No conflict of interest Alonso, Inmaculada: No conflict of interest
Palau et al. (Thu,) studied this question.